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JPG to PDF under 4 MB
To make a PDF under 4 MB, PixelFit compresses the JPG to at most 3,999,260 bytes and wraps it in a one-page PDF with about 740 bytes of PDF structure, 4,000,000 bytes or less in total. Measured: an A4 scan at 150 DPI fits at quality 95; a 4:3 photo at about 5,075 × 3,806 (extrapolated) pixels (quality 75).
PDF under 4 MB
PDF · under 4 MB (at most 4,000,000 bytes) · original pixel size · white background
PixelFit aims at 4,000,000 bytes or less, so the file passes whether the form counts 1 MB as 1,000,000 or 1,048,576 bytes.
Fit, background and padding white background · page the size of the picture
Saving presets is part of Pro.
The result appears here: the exact byte count, pixel size and quality, the size before and after, a preview and a download button.
The batch kit (one ZIP for up to 500 photos, several photos merged into one PDF) is part of Pro.
Where the 4 MB go in a JPG-to-PDF file
Of the 4,000,000 bytes that pass as 4 MB whether a megabyte is 1,000,000 or 1,048,576 bytes, PDF structure takes 740 bytes for one A4 page (computed with PixelFit's own writer), leaving 3,999,260 bytes, 99.9 %, for the JPEG; ten pages leave 399,473 bytes each.
For one photo that is plenty: a full 12 MP phone photo fits at quality 88 (extrapolated). The limit matters when many pages share it.
How many pages fit in a 4 MB PDF
The 4,000,000 bytes of 4 MB, less 740 bytes of PDF structure for the first page and about 502 for each extra one, shared evenly.
| Pages | JPEG bytes per page | Max A4 DPI at q50 | Max A4 DPI at q75 | A4 at 150 DPI |
|---|---|---|---|---|
| 1 page | 3,999,260 | 600 DPI or more* | 600 DPI or more* | quality 95+ |
| 2 pages | 1,999,381 | 600 DPI or more* | 538 DPI* | quality 95+ |
| 3 pages | 1,332,752 | 588 DPI* | 418 DPI* | quality 95+ |
| 5 pages | 799,451 | 421 DPI* | 304 DPI* | quality 95+ |
| 10 pages | 399,473 | 268 DPI* | 198 DPI | quality 87 |
| 20 pages | 199,485 | 168 DPI | 126 DPI | quality 61 |
| 50 pages | 79,491 | 91 DPI | 71 DPI | no: 1.6× over at q30 |
| 100 pages | 39,491 | 61 DPI | 48 DPI | no: 3.2× over at q30 |
Phone photos in one PDF under 4 MB
Largest 4:3 photo per page, in pixels, when 1 to 10 photos share 4,000,000 bytes; "full" means a 12 MP phone photo keeps all its pixels (the tool never enlarges).
| Photos | Quality 60 | Quality 75 | Quality 90 |
|---|---|---|---|
| 1 photo | full 4032 × 3024* | full 4032 × 3024* | 3,845 × 2,883* |
| 2 photos | 3,992 × 2,994* | 3,431 × 2,573* | 2,618 × 1,963 |
| 3 photos | 3,178 × 2,383* | 2,729 × 2,046 | 2,097 × 1,572 |
| 5 photos | 2,385 × 1,788 | 2,053 × 1,539 | 1,603 × 1,202 |
| 10 photos | 1,650 × 1,237 | 1,427 × 1,070 | 1,125 × 843 |
A4 and Letter pixel sizes against 4 MB
One typed page per DPI: its pixels, the quality it gets alone in 4 MB, and how many fit at quality 75.
| DPI | A4 pixels | One A4 page under 4 MB | Letter page | Pages at q75 |
|---|---|---|---|---|
| 72 DPI | 595 × 842 | quality 95+ | quality 95+ | 49 |
| 100 DPI | 827 × 1169 | quality 95+ | quality 95+ | 28 |
| 150 DPI | 1240 × 1754 | quality 95+ | quality 95+ | 15 |
| 200 DPI | 1654 × 2339 | quality 95+ | quality 95+ | 9 |
| 300 DPI | 2480 × 3508 | quality 95+ | quality 95+ | 5 |
Readable pages and photos in 4 MB
At 4 MB, 23 typed A4 pages scanned at 150 DPI fit at quality 50 or better, and 15 at 200 DPI: room for a long multi-page document. 8 photos of 1600 × 1200 at quality 70 also fit.
A single page at 300 DPI gets quality 95+; there is room to keep the scan near its original quality. Full-size 12 MP photos (4032 × 3024, our landscape sample, extrapolated from encodes up to 3000 px) that fit together in 4 MB: 1 at quality 60, 1 at quality 75, none at quality 90.
One image free, several merged with Pro
Free: each image becomes its own one-page PDF under 4 MB. Pro: several images merged into one PDF under 4 MB, on your device; 10 pages get 399,473 bytes of JPEG each.
How to turn a JPG into a PDF under 4 MB
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Open the tool above
Preset: PDF output, at most 4 MB.
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Add the JPG
Drop, paste or pick it (PNG, WebP and HEIC work too).
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Choose the page
Keep the picture's own size or fit it on A4 or Letter.
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Download
name-4mb.pdf arrives with its exact byte count (4,000,000 bytes or less).
Forms with a 4 MB PDF limit
Upload specs in our dataset with a PDF limit of exactly 4 MB. Verify with the official notice before you submit.
4 MB PDF uploads
Sources
- Measured by PixelFit with sharp 0.35.5 / libvips 8.18.7 on 31 October 2026.
- Samples, Wikimedia Commons, checked 31 October 2026: typed page (public domain) commons.wikimedia.org/w/index.php?curid=194775753; landscape (CC0 1.0) commons.wikimedia.org/w/index.php?curid=154070378
- Paper sizes, Markus Kuhn, checked 31 October 2026: cl.cam.ac.uk/~mgk25/iso-paper.html
- PDF format, Library of Congress, checked 31 October 2026: loc.gov/preservation/digital/formats/fdd/fdd000474.shtml
Frequently asked questions
How do I convert a JPG to PDF under 4 MB?
Drop the JPG into the tool on this page, preset to PDF under 4 MB: the picture is compressed to 3,999,260 bytes or less, so the PDF ends at or below 4,000,000 bytes.
Can I convert JPG to PDF for free?
Yes, one image per PDF, with no upload. Under 4 MB a full 12 MP phone photo keeps all its pixels at quality 88; merging several JPGs is Pro.
How many pages fit in a 4 MB PDF?
About 23 typed A4 pages scanned at 150 DPI at quality 50 or better, or 15 at 200 DPI; 8 photos of 1600 × 1200 at quality 70.
What DPI should a scan have for a 4 MB PDF?
One typed A4 page fits under 4 MB at 600 DPI or more (extrapolated) at quality 50, and at 600 DPI or more at quality 75; any of the usual 72 to 300 DPI settings works, up to 300 DPI.
Why is the PDF bigger than my JPG?
A PDF wraps the JPEG in page, image and cross-reference objects: 740 bytes for one page in PixelFit's writer, about 502 more per added page.
Related
Other PDF size limits
- JPG to PDF under 3 MB 17 A4 pages at 150 DPI
- JPG to PDF under 2 MB 11 A4 pages at 150 DPI
- JPG to PDF under 1.5 MB 8 A4 pages at 150 DPI
- JPG to PDF under 5 MB 29 A4 pages at 150 DPI
- JPG to PDF under 10 MB 59 A4 pages at 150 DPI
More for 4 MB
- Compress an image to 4 MB Same limit, image output
- JPG to PDF: what changes Format facts
- Image resizer with KB target Any size and format
Other formats to PDF
Pixel sizes that fit 4 MB
- A3 (297×420 mm) about 3.48 MB as a quality-75 JPG
- 4000×4000 square about 3.23 MB as a quality-75 JPG
- 5120×2880 (5K) about 3 MB as a quality-75 JPG